GPS Interference Issue Back on the Table

 - May 12, 2020, 11:04 AM

A coalition of industries that rely on GPS is concerned that the U.S. Federal Communications Commission’s (FCC) approval of Ligado Networks' telecommunications system will risk interference with GPS signals. Ligado is the new company formed after LightSquared’s bankruptcy in 2012, and it took over LightSquared’s L-band network. Ligado does not agree that there is any risk of GPS interference in the range of frequencies covered by its FCC license.

The coalition’s issues are summarized in a submission to a Senate Armed Services Committee hearing held on May 6, “Department of Defense Spectrum Policy and the Impact of the FCC's Ligado Decision on National Security.” The issues include ignoring national security, risking public safety, economic impact, and outsourcing enforcement of GPS interference issues to Ligado.

The public safety issue is perhaps the most important as it addresses the widespread use of GPS and reintroduces the GPS interference issues that dogged the LightSquared FCC application.

For one example, the coalition letter states that “Use of GPS is fundamental to the continued safe and effective operation of our industries and professions, where false or missing GPS data can easily result in a tragic accident.” The letter goes on, “Unfortunately, the FCC order does not use recognized standards to safeguard GPS users, but instead implements its own measure of performance based on Ligado-commissioned testing of a limited number of GPS devices. Without the necessary assurance at this stage, the FCC is creating a dangerous dynamic and precedent that the appropriate action is only taken after interference, and perhaps an accident, has occurred.”

The coalition letter also brings up the potential for disruptions to satellite communications, claiming that the FCC order never evaluated Ligado’s impact on satcom. “A single Ligado transmitter could easily disable or disrupt satellite communications on an aircraft that carries hundreds of passengers, and other users requiring reliable communications coverage.”

Ligado disagrees and, in a letter to the committee, pointed out that the FCC granted “our spectrum license applications after a lengthy public proceeding involving years of public comment and expert review.” Ligado also expressed disappointment that no one from Ligado or the FCC was invited to testify at the hearing.

The summary of Ligado’s letter noted that the FCC and Department of Commerce rules covering GPS interference have not changed. “Nevertheless,” Ligado explained, “the FCC imposed additional conditions to ensure that GPS devices will continue to be protected from any activity that could affect GPS operations.

"Specifically, the FCC directed Ligado to provide protections to GPS devices using its spectrum by imposing stringent coordination, cooperation, and replacement obligations on Ligado, so that Ligado bears the burden of ensuring that no device using Ligado’s spectrum will be negatively impacted. Make no mistake: the obligation is ours, and the burden falls solely on our company. We stand ready to begin working right away with the FCC, the DoD, the Commerce Committee, and other stakeholders to ensure GPS is protected and to advance our progress toward 5G.”